My answer to this question has changed quite a bit over the years, and I expect it to change in the future.
In the past, I would have defined my life based on a mixture of the following things – What did I give back to the community? What achievements/successes have I had? How much am I there for my future kids, family, and friends? What are the sites I have seen and countries I’ve visited? What cultures have I exposed myself to? How does my work impacts the world? What charities have I started or contributed to? What organizations do I volunteer for?
I’ve realized that a lot of these criteria are based on future events and circumstances. In fact, my old definition perfectly reflected my mindset which was almost always living for the future. Living for a future period when x or y or z would happen so I could be happy and I could say that my life is valuable.
Over the past decade, I’ve come to realize that the future NEVER comes in the way that one would expect it to, that life is messy, and that living for the future is a strategy that doesn’t work. (Without going on too much of a tangent, I think there is a fine line between planning for the future and having goals compared to living for the future.). Life is unfolding right now and it can end in any moment and it is important to make sure any measure of my life is reflective of the present moment.
I measure my life today largely based on the people in my life right now and the types of connections I have. I am not really focused on having to do certain things in order to make my life worth living. I think that as long as I derive joy from living in the moment by pursuing things that get me in a flow, by surrounding myself with awesome people, and slowing down to be compassionate and connect with everyone this life will have been lived well.
If I were to die today I want people to remember how I took the extra moment to connect with them when they needed a friend, I want people to remember me for having a positive attitude, I want people to remember me for being compassionate and loving. All these things have nothing to do with obtaining something, these are things that I can express starting today and right now. As long as I focus on embodying these qualities in every moment I believe the rest of the stuff like giving back, changing the world etc. is just a positive by product from living in the moment.